Odd-parity electronic order in the strongly correlated and spin-orbit coupled metal Cd2Re2O7

Over the past several years, correlated electron systems with strong spin-orbit coupling have become a promising platform for realizing fundamentally new quantum states of matter. The majority of studies carried out in this burgeoning area have focused on exotic insulating phases such as topological Kondo insulators, Kitaev spin liquids, and topological Mott insulators. Recently, however, it has been theoretically predicted that novel metallic phases can also emerge in this regime. These newly predicted phases are characterized by spontaneously broken spatial inversion symmetry and are composed of charge carriers that exhibit spin-momentum locking and associated Fermi surface spin textures. Beyond their interest as fundamentally new states of matter, parity-odd electronic liquids are also predicted to be gateways to other exotic phases such as topological superconductivity. In this talk, I will discuss the first experimental observation of such odd-parity electronic order in the strongly spin-orbit coupled correlated metal Cd₂Re₂O₇ using optical second harmonic generation. I will also discuss our use of coherent phonon spectroscopy to uncover an intricate coupling between the electronic and lattice degrees of freedom in this material, leading to phonons with a diverging damping rate at the critical temperature of the phase transition.